Sprinkle the salt over the cabbage, mix and leave for 10 minutes.
Mix the pork, spring onion, ginger, garlic, soy sauce, sesame oil and sake in a bowl. Squeeze any excess liquid from the cabbage. Add the cabbage to the pork mixture and combine well.
Lay as many gyoza wrappers as you have room for on a clean work surface and have a small bowl of water to hand.